STUDIES ON THE USE OF NITROAROMATICS AS LABELS FOR LIQUID CHROMATOGRAPHY/ELECTROCHEMISTRY
Abstract
The use of nitroaromatic labels in conjunction with liquid chromatography/electrochemistry (LCEC) has been examined. Derivatives containing nitroaromatic moieties were found to be ideally suited to determination of LCEC, with detection limits typically an order of magnitude lower than obtainable using absorbance detection. In particular, the advantageous use of nitroaromatic reagents for determination of carbonyl compounds (e.g. aldehydes and ketones) and amino acids was demonstrated. Several common nitroaromatic reagents for derivatizing amines were evaluated in terms of chemical and analytical behavior. Trinitrobenzene sulfonic acid was identified as the most suitable in both respects. Several nitroaromatic isothiocyanates were prepared and characterized for use as reagents for protein sequence determination. Both phenyl and benzyl isothiocyanates were employed. While analytical properties of the nitroaromatic thiohydantoins were highly favorable, chemical properties appeared to eliminate all from serious consideration. The benzyl derivatives underwent sluggish cyclization, while the phenyl reagent was too reactive and produced unacceptable levels of interferences. The use of a dual glassy carbon transducer for determination of nitroaromatics was demonstrated. The dual electrode approach allowed sensitive determination without interference from dissolved oxygen. It was concluded that appropriate reducible species could be detected without prior deoxygenation of samples or mobile phases, and with only minor loss in performance.
Degree
Ph.D.
Subject Area
Analytical chemistry
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